Pump system

ABSTRACT

A pump system comprising a vacuum pump and a cooling element connected to said vacuum pump. A coolant feed and a coolant discharge are connected to the cooling element for the purpose of cooling said vacuum pump by virtue of receiving and discharging heat using a coolant. The coolant feed and coolant discharge are connected to a heat exchanger such that heat is transferred from the coolant discharge to said coolant feed.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to a pump system, in particular for pumping gases/vapors near the condensation point and/or near the deposition point.

2. Discussion of the Background Art

In some coating processes (e. g., in the semiconductor industry or during the manufacture of flat screens) gases/vapors near the condensation point (transition from the gaseous state to the liquid state) and/or near the deposition point (transition to the solid state) are delivered. In particular the second case is critical for vacuum pumps since the solid bodies produced collect in the form of dusts or deposits in the vacuum pump and clog the latter. This applies above all to the discharge side of the vacuum pump since here a higher pressure prevails and the vapor is nearer the condensation/deposition point.

One way to avoid this problem is the use of additional gases (e. g. gas ballast, purging gas) for diluting the vapors and keeping their partial pressure adequately low. However, in some applications this solution is not useful since an excessive amount of auxiliary gas would be necessary. In such cases it is recommendable to increase the temperature of the vacuum pump for transporting the delivered substances in the form of gases or vapors through the vacuum pump. Due to the higher pressure the temperature on the discharge side of the exhaust pipe of the vacuum pump is critical.

In prior art, regulating systems for the cooling water control are used for tempering purposes. These systems set and/or regulate the cooling water flow such that the temperature at a reference location at the vacuum pump (typically on the discharge side) is maintained at a predetermined temperature.

This solution is disadvantageous in that possibly the vacuum pump is supplied with only a low amount of cooling water and/or temporally no cooling water at all. According to the type of vacuum pump, this may lead to inadequate cooling of temperature-sensitive components, such as motor, bearings or electronic components.

Since the exhaust pipe of the vacuum pump must also be kept at a high temperature level, this pipe is normally further separately heated (e. g. by electrically operated heating sleeves). This reduces the energy efficiency of the vacuum pump which results in higher costs.

Another problem encountered in these processes is the use of purging gases which are supplied to the vacuum pump and may cause there, at the supply location, local cooling of the process gas. This may lead to undesired condensation and/or deposition.

It is an object of the present disclosure to provide a pump system, in particular for delivering gases/vapors near the condensation point and/or near the deposition point, where condensation and/or deposition are effectively prevented while the pump system operates reliably and efficiently.

SUMMARY

The pump system according to the present disclosure comprises a vacuum pump. The pump system comprises at least one vacuum pump such that a pump system made up of a plurality of vacuum pumps connected with each other is also included. The vacuum pump is in particular a dry-compressing pump. However, the disclosure described below is essentially independent of the type of pump such that the present disclosure includes substantially all pump types. The vacuum pump of the pump system according to the present disclosure is a conventional vacuum pump which usually comprises a suction chamber in which a movable pump element is arranged for delivering a medium from an inlet to an outlet. The movable pump element is a rotating rotor or a piston, for example. In particular at the rotor at least one pump element is arranged which causes the medium to be delivered. In the pump system according to the present disclosure described here screw pumps, claw pumps, Roots pumps, piston pumps and the like can be used. Further, the pump system according to the present disclosure may comprise, besides positive-displacement pumps, kinetic pump systems, including the hybrid form of lateral channel blowers, as well as molecular pump stages, such as Holweck stages, Siegbahn stages, Gaede pumps and turbomolecular pumps. In particular, the pump system is suitable for generating a vacuum of in particular 10⁻² mbar, preferably 10⁻³ mbar and particularly preferably 10⁻⁶ mbar.

Further, the pump system according to the present disclosure comprises a cooling element which is connected with the vacuum pump for cooling purposes. The cooling element is in particular connected with the housing of the vacuum pump which defines the suction chamber of the vacuum pump. The cooling element comprises a coolant supply pipe and a coolant discharge pipe. Via the coolant supply pipe coolant is supplied to the cooling element and absorbs the heat of the vacuum pump. The heated coolant leaves the cooling element via the coolant discharge pipe. Thus the cooling element cools the vacuum pump by absorbing and discharging of heat by means of the coolant.

According to the present disclosure, a heat exchanger is connected with the coolant supply pipe and the coolant discharge pipe such that the heat absorbed by the coolant is transferred from the coolant discharge pipe to the coolant supply pipe and/or to the coolant fed to the coolant supply pipe.

Thus tempering of the vacuum pump is carried out by means of preheated cooling water. An adequate amount of the preheated cooling water can continuously flow through the vacuum pump. Hence the cooling water supply is not interrupted such that adequate cooling of sensitive components is always guaranteed and thus a homogenization of the heat distribution inside the pump is attained. Thus tempering by means of the preheated cooling water prevents some places of the pump from becoming overcritically hot. At the same time it is not necessary to make available adequately hot cooling water which would have to be heated in an energy-intensive manner. The cooling water is preheated via the heat exchanger by means of the heat of the vacuum pump discharged by the coolant.

In particular, the heat exchanger is connected with a coolant inlet and a coolant outlet. Via the coolant inlet the coolant is fed to the pump system and via the coolant outlet the coolant leaves the pump system. A coolant which is not treated and not tempered can be fed through the coolant inlet to the pump system. Pretreatment, in particular preheating, of the coolant is not required. Thus further construction-related measures at the site of operation of the pump are not required, which helps to save costs and to create a compact pump system.

In particular, the coolant is water, wherein preferably chemical additives can be added to the water to adapt individual properties of the coolant to the requirements of the pump system. Alternatively, the coolant is oil or another synthetic liquid.

In particular, the pump system comprises a first cooling circuit for a first coolant starting at the heat exchanger and extending via the cooling element back to the heat exchanger, as well as a second cooling circuit for a second coolant starting at the coolant inlet and extending via the heat exchanger to the coolant outlet. Thus the heat produced in the vacuum pump is discharged by the first coolant via the first cooling circuit and transferred by the second coolant via the heat exchanger to the second cooling circuit. Then the second coolant leaves the pump system via the coolant outlet. In the heat exchanger not the entire heat is transferred from the first coolant to the second coolant but merely a portion thereof such that residual heat remains in the first coolant and thus preheated coolant is available for the vacuum pump. Preferably, the first coolant and the second coolant may differ from each other such that in the first cooling circuit oil is used as the first coolant and in the second cooling circuit water is used as the second coolant, for example.

Alternatively, in a particularly preferred embodiment, the pump system comprises in particular a single cooling circuit, starting at the coolant inlet and extending via the heat exchanger to the cooling element and back to the heat exchanger and to the coolant outlet. The heat discharged from the vacuum pump by means of the coolant is transferred via the heat exchanger to the coolant in the coolant inlet flowing to the vacuum pump, whereby preheated coolant is made available for the vacuum pump. Thereby in particular a permanent exchange of the coolant flowing through the pump system takes place.

In particular, a regulating valve is arranged in the coolant supply pipe and/or between the coolant inlet and the heat exchanger, which is designed for regulating the flow rate of the coolant. In particular when two cooling circuits are provided, the portion of the heat discharged via the second cooling circuit can be regulated by a regulating valve arranged between the coolant inlet and the heat exchanger. Preferably, the regulating valve is controlled via temperature measurement, wherein during the temperature measurement the housing temperature of the vacuum pump and/or the temperature of the coolant in the coolant supply pipe, immediately before it enters the vacuum pump, are preferably measured.

In particular, the vacuum pump comprises a purging gas feed pipe for providing purging gas for the pumping process. The purging gas feed pipe is connected with the heat exchanger and/or the coolant discharge pipe for preheating the purging gas such that heat discharged from the vacuum pump by means of the coolant is transferred to the purging gas. Thus the purging gas is preheated before it is introduced into the vacuum pump such that the process gas is not locally cooled which could lead to condensation or deposition of the process gas. The heat produced by the vacuum pump is transferred to the purging gas such that an additional device for preheating the purging gas is not required and existing heat produced by the vacuum pump can be efficiently used for preheating the purging gas.

A second independent disclosure relates to a pump system having a vacuum pump, wherein the vacuum pump comprises an inlet and an outlet. The pump system comprises at least one vacuum pump such that a pump system made up of a plurality of vacuum pumps connected with each other is also included. The vacuum pump is in particular a dry-compressing pump. However, the disclosure described below is essentially independent of the type of pump such that the present disclosure includes substantially all pump types. The vacuum pump of the pump system according to the present disclosure is a conventional vacuum pump which usually comprises a suction chamber in which a movable pump element is arranged for delivering a medium from an inlet to an outlet. The movable pump element is a rotating rotor or a piston, for example. In particular at the rotor at least one pump element is arranged which causes the medium to be delivered. In the pump system according to the present disclosure described here screw pumps, claw pumps, Roots pumps, piston pumps and the like can be used. Further, the pump system according to the present disclosure may comprise, besides positive-displacement pumps, kinetic pump systems, including the hybrid form of lateral channel blowers, as well as molecular pump stages, such as Holweck stages, Siegbahn stages, Gaede pumps and turbomolecular pumps. In particular, the pump system is suitable for generating a vacuum of in particular 10⁻² mbar, preferably 10⁻³ mbar and particularly preferably 10⁻⁶ mbar.

According to the present disclosure, the pump system comprises a purging gas feed pipe which is connected with the vacuum pump for providing purging gas for the pumping process.

According to the present disclosure, the outlet has connected therewith an outlet heating for heating the outlet. The purging gas feed pipe is connected with the outlet heating such that heat produced by the outlet heating is transferred to the purging gas. Thus a preheated purging gas is provided for the pump system by using the outlet heating such that further heating elements are not required. Hence the heat produced by the outlet heating is efficiently used for preheating the purging gas. Alternatively, the outlet has connected therewith an exhaust pipe which comprises an exhaust pipe heating for heating the exhaust pipe. Here, the purging gas feed pipe is connected with the exhaust pipe heating such that heat produced by the exhaust pipe heating is transferred to the purging gas. Here, too, heat already produced is utilized for preheating the purging gas such that the pump system is efficiently designed. In particular, as a constructively simple measure, it comprises only one heating by means of which the purging gas is at least indirectly heated.

In particular, both an outlet heating and an exhaust pipe heating are provided which particularly preferably are configured as a common outlet/exhaust pipe heating element. Thus only a single heating element is provided which simultaneously heats the outlet and the exhaust pipe. The outlet/exhaust pipe heating element preheats, via the purging gas feed pipe connected therewith, the purging gas for the pumping process.

In particular, the purging gas feed pipe helically surrounds the outlet and/or the exhaust pipe. Thus an effective heat transfer from the outlet heating and/or the exhaust pipe heating and/or the outlet/exhaust pipe heating element is guaranteed.

In particular, the purging gas feed pipe is partly surrounded by the outlet heating and/or the exhaust pipe heating and preferably the outlet/exhaust pipe heating element. This arrangement ensures an efficient heat transfer. At the same time, the heatings and/or the heating element may be surrounded by an insulation such that as little heat as possible is dissipated to the environment.

In particular, a cooling element is connected with the vacuum pump, wherein the cooling element comprises a coolant supply pipe and a coolant discharge pipe for cooling the vacuum pump by absorbing and discharging of heat by means of a coolant. The coolant supply pipe and the coolant discharge pipe are connected with a heat exchanger.

In particular, the pump system is configured according to the features of the first disclosure.

A third independent disclosure relates to a pump system having a vacuum pump. The pump system comprises at least one vacuum pump such that a pump system made up of a plurality of vacuum pumps connected with each other is also included. The vacuum pump is in particular a dry-compressing pump. However, the disclosure described below is essentially independent of the type of pump such that the present disclosure includes substantially all pump types. The vacuum pump of the pump system according to the present disclosure is a conventional vacuum pump which usually comprises a suction chamber in which a movable pump element is arranged for delivering a medium from an inlet to an outlet. The movable pump element is a rotating rotor or a piston, for example. In particular at the rotor at least one pump element is arranged which causes the medium to be delivered. In the pump system according to the present disclosure described here screw pumps, claw pumps, Roots pumps, piston pumps and the like can be used. Further, the pump system according to the present disclosure may comprise, besides positive-displacement pumps, kinetic pump systems, including the hybrid form of lateral channel blowers, as well as molecular pump stages, such as Holweck stages, Siegbahn stages, Gaede pumps and turbomolecular pumps. In particular, the pump system is suitable for generating a vacuum of in particular 10⁻² mbar, preferably 10⁻³ mbar and particularly preferably 10⁻⁶ mbar.

According to the present disclosure, the vacuum pump is connected with a cooling element, wherein the cooling element comprises a coolant supply pipe and a coolant discharge pipe for cooling the vacuum pump by absorbing and discharging of heat by means of the coolant.

According to the present disclosure, the coolant supply pipe comprises a heating element for preheating the coolant. Thus the coolant supplied to the vacuum pump is preheated such that even in the case of a higher pump temperature adequate cooling of temperature-sensitive components is always guaranteed and the heat distribution inside the vacuum pump is homogenized such that damage to temperature-sensitive components can be prevented.

In particular, the coolant supply pipe and the coolant discharge pipe are connected with a heat exchanger. Thus the heat of the coolant discharge pipe is transferred to the coolant supply pipe. However, this only takes place when the vacuum pump has reached a certain operating temperature. Thus in particular the heating element according to the present disclosure ensures during the starting phase of the vacuum pump that adequately preheated cooling water is fed to the vacuum pump. Once sufficient heat has been transferred from the coolant discharge pipe via the heat exchanger to the coolant supply pipe, the heating element can be switched off.

In particular, the pump system is configured according to the features of the first disclosure.

In particular, the vacuum pump comprises an inlet and an outlet. Further, the vacuum pump is connected with a purging gas feed pipe for providing purging gas for the pumping process. The outlet has connected therewith an outlet heating for heating the outlet, wherein the purging gas feed pipe is connected with the outlet heating such that heat produced by the outlet heating is transferred to the purging gas and the purging gas is thus preheated before being introduced into the vacuum pump. Alternatively, the outlet has connected therewith an exhaust pipe which, in turn, is connected with an exhaust pipe heating for heating the exhaust pipe. Here, the purging gas feed pipe is connected with the exhaust pipe heating such that heat produced by the exhaust pipe is transferred to the purging gas. Here, too, the produced heat is efficiently utilized by preheating the purging gas. A preheated purging gas ensures that no local cooling of the process gas occurs, which would lead to condensation or sublimation inside the vacuum pump.

In particular, the pump system is configured according to the features of the second disclosure.

In particular, the heating element is arranged downstream of the heat exchanger.

In particular, the heating element is an electric heating element. This ensures a simple design. Alternatively or additionally, the heating element is the outlet heating, the exhaust pipe heating and/or the outlet/exhaust pipe heating element. Thus the heat produced by the outlet heating and/or the exhaust pipe heating and/or the outlet/exhaust pipe heating element is used for preheating the coolant such that the produced heat can be efficiently utilized.

In particular, the features of the individual disclosures can be freely combined with each other such that an efficient pump system is realized which ensures during the delivery of gases and vapors near the condensation point and/or the deposition point that neither condensation nor deposition occur. Thus a reliable operation of the pump system is always guaranteed and hence it is ensured that no condensing or depositing process gas can clog or even block the vacuum pump.

A fourth independent disclosure relates to a method for preheating a coolant for a vacuum pump. In the method according to the present disclosure, a least a portion of the heat absorbed by the coolant, as it passes through the vacuum pump, is transferred to the coolant supplied to the vacuum pump. Thus the coolant does not discharge the entire absorbed heat but a portion of the absorbed heat is used for preheating the supplied coolant.

In particular, the method is carried out using a pump system according to the first disclosure.

In particular, the coolant is preheated by a heating element before it passes through the vacuum pump for cooling the vacuum pump.

In particular, the heating element is switched on when the vacuum pump does not produce sufficient heat such as during startup of the pump or during stopping. In this situation it is not possible to transfer a sufficient amount of heat, absorbed by the coolant as it passed through the vacuum pump, to the supplied coolant for adequately preheating the coolant before it passes through the vacuum pump. Once the heat discharged from the vacuum pump suffices for preheating the supplied coolant, the heating element is preferably switched off.

In particular, the method is carried out using a pump system according to the third disclosure.

A fifth independent disclosure relates to a method for preheating a coolant for a vacuum pump, wherein the coolant is preheated by a heating element before it passes through the vacuum pump.

In particular, the method is carried out using a pump system according to the third disclosure.

A sixth independent disclosure relates to a method for preheating a purging gas for a vacuum pump, wherein the purging gas is preheated by the heat produced by the vacuum pump and/or by the heat produced by a heating element.

In particular, the method is carried out using a pump system according to the second disclosure.

In particular, the heat produced by the vacuum pump is transferred by means of a coolant to the purging gas.

In particular, the heating element heats an outlet and/or an exhaust pipe connected with the outlet. This is carried out by means of the same heating element which also preheats the purging gas such that the heat produced by the heating element is efficiently utilized.

In particular, the features of the methods of the disclosures four to six can be freely combined such that an efficient method is realized which guarantees reliable operation and which effectively prevents condensation and deposition of process gas.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereunder preferred embodiments of the present disclosure are described in detail with reference to the drawings in which:

FIG. 1 shows a first embodiment of the pump system having a heat exchanger;

FIG. 2 shows a second embodiment of the pump system having a heat exchanger;

FIG. 3 shows a third embodiment of the pump system having a heating element;

FIG. 4 shows a fourth embodiment of the pump system having a heat exchanger and a heating element;

FIG. 5 shows a fifth embodiment of the pump system having a heat exchanger and a heating element;

FIG. 6 shows a sixth embodiment of the pump system with purging gas preheating;

FIG. 7 shows a detailed view of the purging gas preheating;

FIG. 8 shows a seventh embodiment of the pump system having two heating elements;

FIG. 9 shows an eighth embodiment of the pump system with purging gas preheating and a heat exchanger; and

FIG. 10 shows a ninth embodiment of the pump system with purging gas preheating and a heat exchanger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present disclosure, the pump system 10 comprises at least one vacuum pump 12 having an inlet 14 and an outlet 16. A further vacuum pump may be connected with the inlet 14 and/or the outlet 16.

The vacuum pump 12 has connected therewith a cooling element 18 which is fluidically connected with a coolant supply pipe 20 and a coolant discharge pipe 22. Via the coolant supply pipe 20 a coolant is fed to the cooling element 18 where it absorbs heat produced by the vacuum pump 12 and is then discharged via the coolant discharge pipe 22 from the vacuum pump 12.

The coolant supply pipe 20 and the coolant discharge pipe 22 are connected with a heat exchanger 24. The coolant supply pipe 20 and the coolant discharge pipe 22 constitute a first coolant circuit 26. A coolant inlet 28 and a coolant outlet 30 are connected with the heat exchanger 24. The coolant inlet 28 and the coolant outlet 30 constitute a second cooling circuit 27 which is connected merely via the heat exchanger 24 with the first cooling circuit 26 and is not fluidically connected therewith. Heat of the vacuum pump 12 absorbed by the first cooling circuit 26 is transferred via the heat exchanger 24 to the second cooling circuit 27. Via a coolant, which enters through the coolant inlet 28, the heat exchanger 24 absorbs this heat and the coolant leaves the pump system via the coolant outlet 30 such that the absorbed heat is effectively discharged.

In the coolant inlet 28 a regulating valve 32 is provided which regulates the flow rate of the coolant passing through the second cooling circuit 27, thereby also regulating the heat discharged via the second cooling circuit 27. Thus the heat remaining in the first cooling circuit 26 can be adjusted via the regulating valve 32 such that a coolant preheated via the coolant supply pipe 20 is fed to the cooling element 18. Preferably, the regulating valve 32 is controllable as a function of the temperature at the cooling element 18, for which purpose a temperature measuring sensor 34 is arranged in the region of the cooling element 18. Other locations for the temperature sensor would be the coolant supply pipe 20 as well as the housing of the vacuum pump 12, for example.

Of course, further regulating valves may be provided for exactly controlling the cooling of the vacuum pump. For the sake of simplicity and a better understanding these regulating valves have been omitted. Thus regulating valves may also be provided in the first cooling circuit 26, for example.

Hereunder similar or identical components are designated by the same reference numerals.

In a second embodiment, shown in FIG. 2, the pump system 36 merely comprises one cooling circuit. From the coolant inlet 28 the coolant is fed to the heat exchanger 24 and is supplied from there via a coolant supply pipe to the cooling element 18 connected with the vacuum pump 12. Via the cooling element 18 the coolant absorbs the heat produced by the vacuum pump 12 and is supplied via a coolant discharge pipe 22 back to the heat exchanger 24. In the heat exchanger 24 the heat of the vacuum pump 12 absorbed by the coolant in the cooling element 18 is at least partly transferred to the coolant in the coolant supply pipe 20 flowing to the vacuum pump 12. From the heat exchanger 24 the coolant leaves the pump system via the coolant outlet 30. When the temperature of the coolant at the coolant inlet is 20°, for example, the coolant is heated in the heat exchanger 24 to 45°, for example, and is then supplied via the coolant supply pipe 20 to the cooling element 18. In the cooling element 18 the coolant absorbs the heat produced by the vacuum pump 12 thus being heated to 60°, for example. After the transfer of this absorbed heat to the inflowing coolant in the heat exchanger, the heat contained in the coolant is reduced such that the coolant has a temperature of only 45°, for example, such that a coolant of 45°, for example, leaves the pump system 30 via the coolant outlet 30.

In the pump system 30 a regulating valve 38 is provided in the coolant supply pipe 20, which regulating valve is controlled as a function of the temperature of the coolant at the location of the regulating valve 38, for example, thus regulating the flow rate of the coolant passing through the cooling element 18.

The pump system 40 shown in FIG. 3 comprises, besides a regulating valve 38 as described above, a heating element 42 in the coolant supply pipe 20, which heating element is also connected with the coolant inlet 28. A coolant entering via the coolant inlet 28 is preheated by the heating element 42 and is fed via the coolant supply pipe 20 to the cooling element 18. In the pump system 40 the coolant discharge pipe 22 is directly connected with the coolant outlet 30 such that the coolant is directly fed from the cooling element 18 to the coolant outlet 30.

In the pump system 44 shown in FIG. 4 the heating element 42 is arranged in a first cooling circuit 26 which is coupled via a heat exchanger 24 with a second cooling circuit 27. Thus, when the temperature of the coolant in the first cooling circuit 26 drops, the temperature is increased via the heating element 42 such that always an adequately preheated coolant is fed to the cooling element 18. Via the second cooling circuit 27 the coolant in the first cooling circuit 26 can be cooled by means of the heat exchanger 24.

The pump system 48 of FIG. 5 merely comprises one pump circuit, wherein along with the coolant supply pipe 20 and the coolant discharge pipe 22 a heat exchanger 24 is provided. In addition, at the outlet 16 of the vacuum pump 12 an outlet heating 50 is provided which maintains the outlet 16 of the vacuum pump 12 at an adequate temperature such that in the region of the outlet 16 condensation and sublimation are avoided.

Via an additional pipe 52, in which a valve 54 is arranged, the coolant can be fed from the coolant inlet 28 via the outlet heating 50 to the coolant supply pipe 20. In the coolant supply pipe 20 another valve 56 is arranged. When the temperature of the coolant is too low and the heat produced by the vacuum pump 12 does not suffice for adequately preheating the coolant via the heat exchanger 24, the coolant can be preheated by means of the outlet heating 50, wherein, for this purpose, the valve 54 is at least partly opened, whereas the valve 56 is at least partly closed. Thus the outlet heating 50 is used both for heating the outlet 16 of the vacuum pump 12 and for preheating the coolant.

The pump system 58 shown in FIG. 6 comprises a purging gas feed pipe 60 via which a purging gas is supplied from a purging gas inlet 62 of the pump 12.

Further, the pump system 58 comprises an outlet heating 50. The purging gas feed pipe 60 is connected with the outlet heating 50 such that heat of the outlet heating 50 is transferred to the purging gas and adequately preheats the latter.

The purging gas feed pipe 60 is helically placed around the outlet 16, as shown in FIG. 7, to realize as effective a heat transfer as possible from the outlet heating to the purging gas feed pipe.

Alternatively or additionally, the outlet heating 50 may be a heating element for heating an exhaust pipe which is connected with the outlet 16 of the vacuum pump 12. Further, the outlet 16 and the exhaust pipe may comprise a common heating element which simultaneously heats the outlet 16 and the exhaust pipe.

The pump system 64 of FIG. 8 comprises a cooling element 18 which is connected via a coolant supply pipe 20 with a coolant inlet 28, as well as a coolant discharge pipe 22 which is connected with a coolant outlet 30. In the coolant supply pipe 20 a heating element 42 for preheating the coolant is arranged, the coolant then cooling the vacuum pump 12 via the cooling element 18. Further, the pump comprises a purging gas feed pipe 60 which is connected with an outlet heating 50. Via another pipe 66 the purging gas feed pipe 60 is connected with the heating element 42. Thus purging gas which enters the pump system via the purging gas inlet 62 is first preheated in the heating element 42 which also serves for preheating the coolant. Subsequently, the purging gas is finally preheated in the outlet heating 50 before the purging gas is supplied to the vacuum pump 12. Thereby the heat of both the heating element for the coolant and the outlet heating 50 is utilized for preheating the purging gas. Since the outlet heating normally has higher temperatures than the heating element 42 for preheating the coolant, the purging gas is preferably first supplied through the heating element 42 and then through the outlet heating 50.

The pump system 68 shown in FIG. 9 comprises a first coolant circuit 26 and a second coolant circuit 27 which are connected with each other via a heat exchanger 24. In addition, the pump 12 of the pump system comprises a purging gas feed pipe 60. This pipe is connected with the coolant discharge pipe 22 of the first coolant circuit 26 and in particular helically surrounds the coolant discharge pipe. A purging gas entering via the purging gas inlet 62 then absorbs the heat transferred by the pump 12 via the cooling element 18 to the coolant flowing through the coolant discharge pipe 22. Thereby the purging gas is adequately preheated and supplied via the purging gas feed pipe 60 to the vacuum pump 12. In particular, the purging gas feed pipe 60 helically surrounds the coolant discharge pipe 22.

The pump system 70 of FIG. 10 comprises a coolant circuit where a coolant supply pipe 20 and a coolant discharge pipe 22 are connected via a heat exchanger 24 with a coolant inlet 28 and a coolant outlet 30. In addition, the pump 12 of the pump system 70 comprises a purging gas feed pipe 60. The purging gas feed pipe 60 is connected with the heat exchanger such that heat from the coolant discharge pipe 22 is not only transferred to the coolant supply pipe 20 but also to the purging gas feed pipe 60 such that the purging gas is adequately preheated.

Of course, the features of the individual embodiments can be combined with each other where this is reasonable. The individual exemplary embodiments are not to be construed as an exhaustive description of the respective pump systems but may be supplemented by features of the other embodiments.

Although the disclosure has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the disclosure be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope of the disclosure as defined by the claims that follow. It is therefore intended to include within the disclosure all such variations and modifications as fall within the scope of the appended claims and equivalents thereof. 

1. A pump system comprising a vacuum pump, a cooling element connected with said vacuum pump and having a coolant supply pipe and a coolant discharge pipe, for cooling said vacuum pump by absorbing and discharging of heat by means of a coolant, wherein said coolant supply pipe and said coolant discharge pipe are connected with a heat exchanger such that heat is transferred from said coolant discharge pipe to said coolant supply pipe.
 2. The pump system according to claim 1, wherein the heat exchanger is connected with a coolant inlet and a coolant outlet.
 3. The pump system according to claim 2, wherein a first cooling circuit for a first coolant starting at the heat exchanger and extending via the cooling element back to said heat exchanger, and a second cooling circuit for a second coolant starting at the coolant inlet and extending via said heat exchanger to the coolant outlet are provided such that heat discharged from the vacuum pump by the first coolant via said first coolant circuit is transferred by means of the second coolant via said heat exchanger to said second cooling circuit.
 4. The pump system according to claim 2, wherein a single cooling circuit starting at the coolant inlet and extending via the heat exchanger to the cooling element and back to said heat exchanger and to the coolant outlet is provided such that heat discharged from the vacuum pump the coolant is transferred via said heat exchanger to the coolant in the coolant supply pipe.
 5. The pump system according to claim 1, wherein in the coolant supply pipe and/or between the coolant inlet and the heat exchanger a regulating valve for regulating the flow rate of the coolant is arranged.
 6. The pump system according to claim 1, wherein a purging gas feed pipe connected with the vacuum pump for providing purging gas for the pumping process is provided, wherein said purging gas feed pipe for preheating the purging gas is connected with the heat exchanger and/or the coolant discharge pipe such that heat discharged from said vacuum pump the coolant is transferred to the purging gas.
 7. A pump system comprising a vacuum pump, wherein said vacuum pump comprises an inlet and an outlet, a purging gas feed pipe connected with said vacuum pump for providing purging gas for the pumping process, an outlet heating connected with said outlet for heating said outlet or an exhaust pipe connected with said outlet, which exhaust pipe is connected with an exhaust pipe heating for heating said exhaust pipe, wherein said purging gas feed pipe is connected with said outlet heating or said exhaust pipe heating such that heat produced by said outlet heating or said exhaust pipe heating is transferred to the purging gas.
 8. The pump system according to claim 7, wherein both an outlet heating and an exhaust pipe heating are provided which are configured as a common outlet/exhaust pipe heating element.
 9. The pump system according to claim 7, wherein the purging gas feed pipe helically surrounds the outlet and/or the exhaust pipe.
 10. The pump system according to claim 7, wherein the outlet heating and/or the exhaust pipe heating at least partly surround the purging gas feed pipe.
 11. The pump system according to claim 7, wherein a cooling element connected with the vacuum pump and having a coolant supply pipe and a coolant discharge pipe is provided for cooling said vacuum pump by absorbing and discharging of heat by a coolant, wherein said coolant supply pipe and said coolant discharge pipe are connected with a heat exchanger such that heat is transferred from said coolant discharge pipe to said coolant supply pipe.
 12. The pump system according to claim 11, wherein the heat exchanger is connected with a coolant inlet and a coolant outlet.
 13. A pump system comprising a vacuum pump, a cooling element connected with said vacuum pump and having a coolant supply pipe and a coolant discharge pipe for cooling said vacuum pump by absorbing and discharging of heat by means of a coolant, and a heating element arranged in said coolant supply pipe for preheating the coolant.
 14. The pump system according to claim 13, wherein the coolant supply pipe and the coolant discharge pipe are connected with a heat exchanger.
 15. The pump system according to claim 14, wherein the heat exchanger is connected with a coolant inlet and a coolant outlet.
 16. The pump system according to claim 13, wherein an inlet and an outlet of the vacuum pump, a purging gas feed pipe connected with said vacuum pump for providing purging gas for the pumping process, an outlet heating connected with said outlet for heating said outlet or an exhaust pipe connected with said outlet, which exhaust pipe is connected with an exhaust pipe heating for heating the exhaust pipe, are provided, wherein said purging gas feed pipe is connected with said outlet heating or said exhaust pipe heating such that heat produced by said outlet heating or said exhaust pipe heating is transferred to the purging gas.
 17. The pump system according to claim 16, wherein both said outlet heating and said exhaust pipe heating are provided which are configured as a common outlet/exhaust pipe heating element.
 18. The pump system according to claim 14, wherein the heating element is arranged downstream of the heat exchanger.
 19. The pump system according to claim 13, wherein the heating element is an electric heating element, the outlet heating, the exhaust pipe heating and/or the outlet/exhaust pipe heating.
 20. A method for preheating a coolant for a vacuum pump, wherein at least a portion of the heat absorbed by the coolant as it passes through said vacuum pump is transferred to the coolant supplied to said vacuum pump.
 21. The method according to claim 20, wherein a pump system according to a pump system comprising: a vacuum pump, a cooling element connected with said vacuum pump and having a coolant supply pipe and a coolant discharge pipe, for cooling said vacuum pump by absorbing and discharging of heat by means of a coolant, wherein said coolant supply pipe and said coolant discharge pipe are connected with a heat exchanger such that heat is transferred from said coolant discharge pipe to said coolant supply pipe is used.
 22. The method according to claim 20, wherein the coolant is preheated by a heating element before it passes through the vacuum pump.
 23. The method according to claim 20, wherein a pump system comprising: a vacuum pump, a cooling element connected with said vacuum pump and having a coolant supply pipe and a coolant discharge pipe for cooling said vacuum pump by absorbing and discharging of heat by means of a coolant, and a heating element arranged in said coolant supply pipe for preheating the coolant.
 24. The method according to claim 20, wherein the heating element is switched on as long as the vacuum pump does not produce sufficient heat for preheating the coolant and said heating element is switched off when the heat discharged from said vacuum pump suffices for preheating the supplied coolant.
 25. A method for preheating a coolant for a vacuum pump, wherein the coolant is preheated by a heating element before it passes through said vacuum pump.
 26. The method according to claim 25, wherein a pump system comprising: a vacuum pump, a cooling element connected with said vacuum pump and having a coolant supply pipe and a coolant discharge pipe for cooling said vacuum pump by absorbing and discharging of heat by means of a coolant, and a heating element arranged in said coolant supply pipe for preheating the coolant is used.
 27. The method according to claim 25, wherein the heating element is switched on when the vacuum pump does not produce sufficient heat for preheating the coolant and said heating element is switched off when the heat discharged from said vacuum pump suffices for preheating the supplied coolant.
 28. A method for preheating a purging gas for a vacuum pump, wherein the purging gas is preheated by the heat produced by said vacuum pump and/or by the heat produced by a heating element.
 29. The method according to claim 28, wherein a pump system comprising: a vacuum pump, wherein said vacuum pump comprises an inlet and an outlet, a purging gas feed pipe connected with said vacuum pump for providing purging gas for the pumping process, an outlet heating connected with said outlet for heating said outlet or an exhaust pipe connected with said outlet, which exhaust pine is connected with an exhaust pipe heating for heating said exhaust pipe, wherein said purging gas feed pipe is connected with said outlet heating or said exhaust pipe heating such that heat produced by said outlet heating or said exhaust pipe heating is transferred to the purging gas is used.
 30. The method according to claim 28, wherein the heat produced by the vacuum pump is transferred by a coolant to the purging gas.
 31. The method according to claim 28, wherein the heating element heats an outlet and/or an exhaust pipe connected with said outlet. 